A finished specimen of indicia set forth in the usual way by use of lead characters is relatively easily corrected after its completion, since lead characters in their solid state are easily interchanged. The problems become intrinsically more difficult with a finished photoprint which is in the form of positive film material. Not only can a symbol once set forth on a light sensitive material no longer be changed on this film, but the symbols and pictures on the film material have no projection surfaces or aligning surfaces, so that corrections must be brought into the proper position either visually or by exposing with additional superimposed markings.
With the so-called smooth print, as long as it is set on large phototype-setting machines which make use of computer data carriers, such as perforated tapes or the like, the correction can be undertaken on devices known as band-fusing fixtures. That process is truly fairly straightforward and also proceeds without great expenditure of time, since it need not be accomplished by visual means, that is by eye control; it can nonetheless be practiced only with very elaborate technical correction machines. Even with phototype-setting machines, the final corrections in actual practice are accomplished by a manual visual process.
With the prior art correction processes which are performed visually, the sections of film in the range of the spot to be corrected will be cut out and glued together after correction, or the spot to be corrected on the film material will be scraped by hand, and a correspondingly large film section with the correction will be pasted over it. The pasting or splicing of film materials still has the disadvantage that even if a relatively thin, so-called stripping film, is brought over the abraded spot to be corrected, the then superimposed copy of the corrected indicia shows the marks of the cut edges in the lighted direction which can't be avoided due to the light reflections along these edges. An attempt was sought to avoid such marks by use of a so-called diffusing foil, which causes a specific diffusion of the light rays. But, by this means, the sharpness of the image is decidedly diminished and a longer time of photographic exposure is required. Only in the instance when photoprint negatives are used for producing photoprint films for printing, or where positives are used as intermediate negatives, is it possible to retouch or remove the cutting edge markings manually by brush and ink. No further argument is needed that this prior art work must be carried out with greatest precision and skill, and thus it represents additional time-consuming operations which must be performed by specially trained personnel.
It should further be observed that the known cutting out of spots to be corrected on a given indicia, whether it is executed manually or with a specially designed fixture, requires as much skill and expenditure of time as the above-mentioned retouching or removing of cutting edge marks with brush and ink. Much patience and skill is also needed for the correction of lines of indicia on photoprint films if the spot to be corrected on the film has been scraped and the resulting bare film surface must be corrected visually by hand with a network of lines.
Advantageously with the familiar cutting out of the faulty spot in the indicia and the subsequent pasting in of the correction, it is clearly seen that the change can be observed during each step in the process, so that one can see at each moment what is being changed. The present invention provides an improved method whereby a correction can be undertaken on positive photoprint film material without requiring time-consuming scraping, cutting, or pasting on the spot to be corrected.